3100 wristox

Participants completed 60 minutes of cycle exercise at an intensity corresponding to 50% normoxic $\dot{\text{V}}{\text{O}}_{\mathrm{2}\text{peak}}$ in each of the 5 testing sessions. Measurement of heart rate, core and skin temperatures, arterial oxygen saturation (SpO₂) and recording of RPE [27 (link)], and thermal sensation (TS; [28 ]) were noted at the end of rest after the venous blood withdrawal and at 10-minute intervals throughout the exercise period. Arterial Hb oxygen saturation (SpO₂) was recorded during respiratory gas collections using a finger-clip pulse oximeter (3100 WristOx, Nonin Medical, Inc., Plymouth, MN, USA). The sensor has a reported accuracy of ±2 digits (manufacturers guide). Physiological strain was calculated using the physiological strain index (PSI; [28 ]). Sweat losses were determined by the change in nude body mass before and after exercise, with sweat volume and mass assumed as being the same (i.e., 1 mL = 1 g; [1 (link)]). Upon completion of each exercise bout a final venous sample (7 mL) was collected while participants remained on the cycle ergometer as previously described.

Unattended nocturnal SpO₂ and snoring signals were recorded in a home environment. The caregivers were shown how to simultaneously start a wearable wrist pulse oximeter (3100 WristOx, Nonin Medical, Inc., Minneapolis, MN, USA). The fingertip sensor was used to obtain the SpO₂ signal (The Novametrix 520 and the 3100 WristOx) and was configured at a 0.5 Hz sampling frequency. Furthermore, the portable sound recorder using linear pulse-code modulation (PCM-D50, Sony Electronics Inc., Tokyo, Japan) was positioned 50 cm above the child’s head when they fell asleep between 21:00 to 24:00 [9 (link)].

Heart rate (HR) and capillary oxyhemoglobin saturation (SpO₂) were measured daily in the morning, using short-range telemetry (iBody, Wahoo Fitness, Atlanta, GA, United States) and finger oximetry device (3100 WristOx, Nonin Medical, Minnesota, United States), respectively. To determine the presence of acute mountain sickness, the participants also completed the Lake Louise acute mountain sickness questionnaire each day (Roach et al., 1993 ). The Lake Louise score (LLS; 0-15) was calculated and the following two criteria were used to diagnose acute mountain sickness: (1) LLS score of ≥3; (2) Headache.